Multiple piston power cylinder



April 25, 1961 J. s. APPLETON MULTIPLE PISTON POWER CYLINDER 2 Sheets-Sheet 1 Filed June 4, 1959 N M O E T VE Nu P A a E 0 J ATTORNEY April 25, 1961 J. s. APPLETON 1, 4

MULTIPLE PISTON POWER CYLINDER Filed June 4, 1959 2 Sheets-Sheet 2 IN V EN TOR.

FIG 5 JOE S. APPLETON wwjpz ATTO RNE'Y MULTIPLE PISTON POWER CYLINDER Joe S. Appleton, 1420 W. 132nd St, Gardenia, Calif. Filed June 4, 1959, Ser. No. 818,095

3 Claims. (Cl. 121-38) This invention pertains to a power cylinder which employs several pistons on a single rod to provide a maximum thrust in a minimum volume.

According to the pro-visions of this invention any number of pistons may be included on a rod which reciprocates with respect to a cylinder. A plurality of annuli, equal in number to the pistons, projects inwardly from the wall of the cylinder and defines with the pistons a number of pressure chambers. The fluid introduced into the cylinder may react directly against the pistons or may be introduced into diaphragms within the pressure chambers. These diaphragms are distensible members having their free edges firmly clamped to avoid loss of pressure or damage or undue wear to these members. The fluid inlet may be provided through the cylinder rather than the rod to give the advantage of a stationary fluid inlet line.

It is an object of this invention to provide maximum force from pressurized fluid within a small volume.

Another object of this invention is to provide a multiplicity of pistons on a single rod to take full advantage of available fluid pressure.

A further object of this invention is to provide distensible members within the pressure chamber which members have their free edges firmly clamped.

An additional object of this invention is to provide fluid connections through circumferential grooves interposed between radial openings to simplify construction and amembly.

Yet another object of this invention is to provide a power cylinder having a stationary fluid inlet line.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawing in which:

Fig. l is a plan view, partially in section, of the power cylinder of this invention,

Fig. 2 is an enlarged fragmentary sectional view of a portion of the arrangement of Fig. 1,

Fig. 3 is an enlarged perspective view of the pressure diaphragm used with the device of Fig. 1,

Fig. 4 is an enlarged transverse sectional view taken along line 44 of Fig. 1 showing the fluid inlet passageways,

Fig. 5 is an enlarged transverse sectional view taken along line 55 of Fig. 1 illustrating the exhaust passageways for fluid displaced by movement of the pistons,

Fig. 6 is an enlar ed fragmentary perspective view of one of the tubular sections of the cylinder showing the exhaust openings and groove,

Fig. 7 is a fragmentary sectional view of a modified form of power cylinder where the pressure diaphragms are open on their outer peripheries and operating fluid is introduced through the cylinder, and

Fig. 8 is a fragmentary sectional view of a further modification of the invention where annular seals are used instead of diaphragms.

As illustrated in Fig. l of the drawing, the device of this invention includes in general a cylinder assembly 1 2,981,234 7 Patented Apr. 25,

which reciprocates a piston rod assembly 2. In the embodiment shown, rod assembly 2 includes three pistons 3, 4 and 5 which receive the force of the pressurized fluid for causing the rod to move. More or less of these pistons could be utilized, it being understood that it is preferred to include at least two pistons so that the pressurized fluid can be utilized to increased eflectiveness. While it is possible to operate the device of this invention with a variety of pressurized fluids, normally the power cylinder will be pneumatically operated.

Rod assembly 2 includes an inner shaft 6, one end 7 of which'is externally threaded, while the opposite end 3 may include a threaded recess 9. Shaft 6 includes an annular shoulder 10 intermediate the ends thereof which is contacted by one side of piston 5 (see Fig. 2). All of the pistons are similar being disc-like members provided with central apertures complementarily received on portion 11 of reduced diameter of the shaft which is adjacent shoulder 10. On the opposite side of piston 5 is a distensible diaphragm or receptacle member 12 which is impervious to the passage of fluid such as air through its radial side walls 13 and 14 and its outer cylindrical wall 15. Preferably member 12 is made of a synthetic rubber such as neoprene. The free inner edges 16' and 17 of member 12 are clamped and sealed between piston 5, a short tubular member 18, and another tubular member 19. This retains edges 16 and 17 against movement as the device is operated, preventing leakage from the pressure chamber and precluding damage to receptacle 12.

Tubular section 19 engages piston 4 at its other end while an additional distensible receptacle 20 is disposed on the opposite side of piston 4. A small annular member 22, similar to member 18, is interposed between the inner edges of chamber 20, while a short tubular member 24 engages the distensible member at its inner edge to complete the clamping of the edges of member 20; A third and similar pressure chamber 25 is included adjacent piston 3, clamped between this piston, annular member 26, and a short tubular section 27. The latter member is internally threaded at its outer end engaging the threads on end 7 of shaft 6. These threads, plus shoulder 10, serve to keep the various elements of the piston rod assembly together and by tightening the threads the elements may be firmly clamped.

The cylinder assembly 1 includes a tubular outer shell 30 having internal threads at one end 31 which engage threads on end member 32 received within that end of the cylinder. The opposite end 33 of member 30 also is internally threaded receiving a second end member 34. These end members retain the elements of the cylinder assembly, holding these members together. Included in the cylinder assembly are short tubular sections 36, 37-, and 38 which are complementary to the inner wall of member 30 and located on the outside perimeter of the pistons and distensible pressure chambers. These members engage and hold annuli 39 and 40 which extend inwardly to act as cylinder heads. The inner edges of members 39 and 40 are in juxtaposition with the outer surface of members 19 and 24, but the latter are slidable relative thereto. End member 34 provides the third cylinder head of the unit. The pistons and cylinder heads, therefore, define three pressure chambers within outer sleeve 30. With the rod retracted at one end of its stroke, as seen in Fig. 1, receptable members 12, 20 and 25 are undistended and complementary to the pressure chambers between the cylinder heads and the pistons.

Pressurized fluid such as compressed air is introduced into the power cylinder of this invention through bore 42 of shaft 6. Radial openings 43, 44, and 45 communicate with bore 42 and allow the compressed air from the shafit to enter annular grooves 46, 47, and 48 in the inner surfaces of members 18, 22, and 26. Additional radial openings 49, 50 and 51 in the latter members connect with the circumferential grooves, thereby directing the pressurized air into the interior of distensible members 12, 2t) and 25. The use of the circumferential grooves avoids alignment problems when the device is assembled and minimizes the amount of precision necessary in forming the parts. Communication between radial openings 43, 44 and 45, and openings 49, 50 and 51 is always assured by the circumferential grooves which are elongated axially.

Distensible receptacles 12, 20 and 25 are rigidly backed on one side by members 34, 39, and 40 of the cylinder assembly, as well as by tubular members 36, 37 and 38 on their outer walls, so that the pressurized fluid reacts against pistons 3, 4 and to move the piston rod assembly axially. Members 12, and expand as the pistons move relative to the cylinder although their inner edges are firmly clamped and retained as described above. The arrangement of this type is completely pressure tight and avoids the use of any type of sealing rings on the pistons which might tend to leak. Air which is displaced by movement of pistons 3 and 4 Within the cylinder passes outwardly through openings 52 and 53 in members 37 and 38 entering outer circumferential grooves 54 and 55 of those members and passing from there through radial openings 56 and 57 in outer tubular member 30. Again the inclusion of a circumferential groove between the radial openings in the two adjoining members simplifies construction and assures proper alignment. As seen in the detailed illustration of Fig. 6, openings 53 may be formed conveniently as notches in the end of the tubular member with groove 55 being recessed inwardly from this end.

Air which is displaced by piston 5 is free to leave the cylinder through opening 58 and end member 32.

When the pressure within the cylinders is released return spring 59, which bears against piston 5 and the inner wall of end member 32, moves the piston rod assembly back to the position of Fig. l where shoulder 60 of shaft 6 is brought into engagement with the outer surface of end member 32. The power cylinder then is ready for another stroke of the piston rod assembly.

It can be seen that this construction provides in a unit of very small diameter a means of producing a large force from available fluid pressure. By including three pistons within the assembly, it is possible to obtain three times the amount of force which would be achieved by a single piston unit of equivalent diameter. Despite this, however, the parts are of relatively simple and economical construction and will not be subject to early failure. The fact that the inner edges of the distensible diaphragm members are held stationary is important in assuring that a positive seal will be made, and also in preventing wear or damage to these members.

According to the arrangement of Fig. 7, the pressurized fluid is brought in through cylinder assembly 61 rather than through piston rod assembly 62, and the distensible pressure diaphragms 63, 64, and 65 are held by the cylinder assembly rather than the piston rod agsembly. Outer tubular member 66 of the cylinder assembly receives short tubular members 67, 68, and 69 in a manner generally similar to the construction previously discussed. Annuli 70 and 71 are engaged by the tubular members extending inwardly from the cylinder to act as cylinder heads within the assembly. End member 72 is illustrated as held in place by a plurality of screws 73 to act as the cylinder head for member 65.

The pressure receptacles 63, 64, and 65 have their free edges on their outer periphery, and these edges are engaged by short tubular members 67, 68 and 69 as well as end member 72. Annularmembers 74, 75 and 76 are included between these inner edges thereby engaging the inner walls of the distensible members.

Air is introduced into the distensible members of this design by means of a longitudinal passageway 77 extend- (2'. ing through end member 72, the walls of the pressure chambers and the annular members between their edges, as well as tubular members 67, 68 and 69, and the outer edges of cylinder heads 70 and '71. Radial passageways 78, 79 and 80 in the annular members communicate with this longitudinal passageway and transmit the pressurized air into the interior of members 62, 63 and 64.

The operation of the device is as before with these members distending and reacting against the pistons 81, 82 and 83. The pistons are secured to shaft 84 by tubular segments 85, 86, 87 and 88, the latter being threaded to the shaft. The force of the air on the pistons, therefore, acts to shift the rod assembly through its stroke.

Air displaced by movement of the pistons leaves the assembly through radial openings 89 in tubular members 85, 86 and 87 on rod 84. These radial openings in turn communicate withannular grooves 90, which through further radial passages 91 join bore 92 of the central rod 84.

This modification of the invention is desirable not only because of the positive seal afforded by the distensible pressure chamber members and the lack of damage or wear to the members resulting from the firm clamping of their free edges, but also enables the use of a stationary air line by connecting the air line to the cylinder rather than to the movable rod. This is advantageous because it assures that the air line will not be flexed continually which might result in leakage or failure after a period of use.

A further modification of the invention may be seen in Fig. 8 where the air again is brought in through the cylinder rather than the rod, but in which sealing rings are employed rather than distensible pressure chamber members. Tubular member 93 of the cylinder assembly threadably engages and member 94 clamping short tubular sections 95, 96 and 97, as well as cylinder heads 98, 99 and 10b, holding these assembled elements against shoulder 101 of cylinder 93. Piston rod 102 is in two sections, 103 and 104 held together at their central portions by threaded sleeve 105. Shoulders 106 and 107 thereby clamp short tubular members 108 and 109 as well as pistons 110, 111, 112 and 113. The pistons all include enlarged peripheral portions which are recessed to receive similar O-rings 114. The inner edge portions of the cylinder heads likewise are enlarged and have O-rings 115 received therein. An additional O-ring 116 is included in end member 102 for its engagement with the outer portion of end section 117 of the piston rod.

Air is introduced into the unit of Fig. 8 through fitting 119 in cylinder 93 from which it passes through passage way 120 in tubular member 95 thereby entering pressure chamber 121 which is located between piston 111 and cylinder head 99. The air can leave this pressure chamber through radial passageways 122 in threaded sleeve 105, and via circumferential groove 123 in that member to radial openings 124 in piston rod 102. It then passes through the central bore 125 of the piston rod assembly and outwardly through passageways 126, 127 and 128 made up of similar combinations of radial openings and circumferential groove. This brings the pressurized air into each of the four pressure chambers 121, 129, 130 and 131 included in this design. The pistons then move relative to the cylinder assembly and the components are sealed by means of the O-rings included. Exhaust for the air displaced by movement of the pistons comes about through grooves and passageways 132, 133, and 134 in the cylinder assembly. End 135 of the cylinder assembly is open so that of course no exhaust passageway is neces sary at that location.

From the foregoing description it is apparent that I have provided an improved power cylinder which takes advantage of a multiplicity of pistons to obtain a maximum thrust in a minimum displaced volume. Without increasing diameter over conventional designs, the force obtained may be multiplied to almost any desired value.

The design allows for the use of stationary air inlet lines and includes the provision of novel distensible pressure chamber members. Construction and assembly of the components are greatly facilitated by the use of circumferential grooves for transmitting fluid between adjacent radial openings.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. A power cylinder comprising a tubular member, a plurality of axially spaced annuli defining cylinder heads therein, a piston rod coaxial with said tubular member and axially movable relative thereto, a plurality of axially spaced radially projecting pistons interposed between said cylinder heads and carried by and movable with said rod for defining with said cylinder heads a plurality of pressure chambers, a distensible hollow receptacle in each of said pressure chambers, each of said receptacles having a free edge portion, means securing said free edge portions against movement, and means for introducing pressurized fluid into said receptacles for causing distension thereof and relative movement between said cylinder and said rod.

2. A power cylinder comprising a tubular member, a plurality of axially spaced annuli extending radially inwardly therefrom, a piston rod coaxial with said annuli and axially slidable relative thereto, a plurality of pistons carried by and projecting radially from said rod and interposed between said annuli for defining with said annuli a plurality of pressure chambers within said tubular member, a distensible receptacle in each of said pressure chambers, each receptacle having a duality of free circumferential edge portions, an annular member interposed between said edge portions at each of said receptacles, means clamping said edge portions of said annular members for sealing the interior of said receptacles and precluding movement of said edge portions relative to said annular members, and means for introducing pressurized fluid through said annular members into said receptacles for causing distension of said receptacles for reacting through said pistons and cylinder heads to cause relative movement between said rod and said tubular member.

3. A device as recited in claim 2 in which said rod is reciprocative through a predetermined stroke, and each receptacle is substantially coterminus with the pressure chamber with which it is associated when said rod is at one end of its stroke, and said receptacles are distended when said rod is at the opposite end of its stroke.

4. A force producing device comprising a tubular member, a plurality of axially spaced parallel annuli carried by and extending inwardly of said tubular member, a shaft extending through the apertures of said annuli in juxtaposition with the inner circumferential edges thereof, said shaft being reciprocative through a fixed stroke, a plurality of discs carried by and extending radially from said shaft with the outer edges thereof in juxtaposition with the inner wall of said tubular member, said discs being interposed between said annuli and defining therewith a plurality of pressure chambers, a distensible receptacle in each of said pressure chambers, each of said receptacles including a duality of spaced radial walls interconnected at one edge by a cylindrical wall, said walls when distended being substantialy complementary to the pressure chamber with which they are associated when said shaft is at one end of its stroke, means sealingly em gaging and holding the opposite edges of said radial walls of said receptacles, and means for introducing pressurized fluid into said receptacles between said opposite edges of said radial walls for thereby causing distension of said receptacles for reacting through said discs and said annuli for causing relative movement of said shaft and said tubular member.

5. A force producing device comprising an outer sleeve member; a shaft reciprocatively received at the axis thereof; tubular means in said sleeve member, said tubular means including a plurality of tubular sections complementary to the inner surface of said sleeve member and received therein, and additional tubular sections complementarily received on said shaft; a plurality of spaced annuli in said sleeve member extending inwardly thereof to define cylinder heads therein, said annuli being held at their outer edges by said first mentioned tubular sections; a plurality of piston heads projecting outwardly from said shaft for defining with said annuli a plurality of pressure chambers, said piston heads being held at their inner edges by said last mentioned tubular sections; a pressure-receiving member of distensible material complementarily received in each of said pressure chambers, each of said pressure-receiving members including a duality of spaced radial walls interconnected at one edge by a cylindrical wall, said tubular means being in engagement with and holding the opposite edges of said radial walls; and means for introducing air into said pressure-receiving members for causing the same to react against said piston heads thereby move said shaft relative to said sleeve member.

6. A device as recited in claim 5 in which for holding said opposite edges of said radial walls one of said tubular sections is interposed between said opposite edges of each of said pressure-receiving members for engaging the inner surfaces of said radial walls, and additional tubular sections engage the outer surfaces of said radial walls at said opposite edges.

7. A device as recited in claim 6 in which said means for introducing air into said pressure-receiving members includes passage means through said tubular sections which are interposed between said opposite edges of said radial walls.

8. A device as recited in claim 6 in which for said means for introducing air into said pressure-receiving members said shaft is provided with an axial opening therein, and spaced radial openings therethrough communicating with said axial opening, said tubular sections which are interposed between said opposite edges of said radial walls of said pressure-receiving members having circumferential groove means therein communicating with said radial openings in said shaft, said tubular sections including radial openings therein interconnecting the interiors of said pressure-receiving and said circumferential groove means thereby to provide communication between said axial opening in said shaft and said pressurereceiving members.

References Cited in the file of this patent UNITED STATES PATENTS 825,866 Rogers July 10, 1906 1,565,767 Westbrook Dec. 15, 1925 2,116,046 Schrnutz May 3, 1938 2,372,813 Darling Apr. 3, 1945 2,383,082 Rossmann Aug. 21, 1945 2,546,596 Haines Mar. 27, 1951 

